Research Shows Many Coronavirus Cases Have No Known Source

PITTSBURGH (KDKA) — With coronavirus case numbers rising, the time for targeted closures has passed, especially when it’s been hard to pinpoint where infections are coming from.

“As we’re seeing an explosion of cases around the world and in the United States, and certainly in our area, I think the targeted restrictions get more difficult to be able to do,” says Dr. Nathan Shively, an infectious diseases specialist at the Allegheny Health Network.


Some transmission has occurred in bars, restaurants, and gyms, but that’s a small sliver of cases.


“Increasingly, it’s not so much that. It’s small gatherings at households where we’re seeing a lot of the transmission happen,” Dr. Shively said.


From Europe to New York City, 75 to 80 percent of positive cases have no known source. Contact tracers can’t pinpoint enough contacts to map the spread.


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“As there are more and more cases to contact trace, it can be overwhelming for the people who are trying track the cases and it can be hard to get in touch with everybody,” Dr. Shively said.


“What we’re seeing locally that’s really disappointing is people are not picking up the phone when contact tracers call. And they’re not being honest about what the exposures have been,” he added.


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And with the long incubation period, people can spread the virus without knowing they have it.


“You can’t contact trace infections that you don’t know about,” Dr. Shively said.


With no clear source of many infections, what public health measures might work?


“The blanket stay-at-home advisory is our best chance at curbing the spread,” Dr. Shively said.


“So any small gathering is an opportunity for that virus to be transmitted person to person,” Dr. Shively said. “So really avoiding any gatherings of people that do not live in your household for now.”


For hospitals to have enough beds and staff, getting the number of cases down is important. Dr. Shively says in our area, we aren’t running out yet, but the upward climb in numbers makes it a concern.